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Improving cyber defence for critical national infrastructure in New Zealand
No full textThe challenge of securing comprehensive services enabled by cyber-physical technologies is becoming increasingly acute. Industrial Control Systems (ICS) and Operational Technology (OT) environments have been in place for several decades. With a combination of computer software, hardware components and industrial/commercial use, these systems are essential in the control and automation of countless industrial procedures and processes that provide indispensable human services in most countries; they make it possible to operate and maintain such operations as the flow of energy through power grids, the treatment and supply of clean water to billions of people, and the maintenance of life saving medical facilities around the world.
This research aims to critically analyse New Zealand's existing cybersecurity strategies and approaches in its defence of Critical National Infrastructure (CNI) organisations operating OT and ICS environments. In this regard, the research draws on international best practices, and proposes a set of hypotheses and actionable insights to fortify cyber resilience for CNIs. It also explores how government-enforced frameworks and standards improve cyber defence for CNIs along with improved accountability. Learnings from this research may be used by policy makers, cyber security leaders, and the government of New Zealand in their consideration of and consultations on academic and pragmatic application, for the development or adoption and enforcement of cyber security standards for CNIs in New Zealand. The essence of this thesis lies in its commitment to contributing to the broader discourse on cybersecurity for OT and ICS environments--particularly in safeguarding critical infrastructures--thereby enhancing the security and welfare of nations in a dynamically changing threat landscape.
To achieve the aforementioned aim, this thesis undertakes an analysis of cyber security standards and frameworks that governments around the globe--especially within the countries represented in the Five Eyes intelligence alliance comprising Australia, Canada, New Zealand, the United Kingdom, and the United States--have enforced for CNIs operating OT and ICS environments. Additionally, the thesis examines whether there are other geographies that are a closer fit culturally and economically for New Zealand to learn from and to emulate when it comes to considering future strategies for improving cyber defence for CNIs. This thesis further explores how systematic, strategic, and collaborative efforts in combination with government enforced frameworks and standards improve cyber defence for CNI and OT and ICS environments. It is guided by comparative analysis, utilizing both qualitative and quantitative data, including policy document reviews, expert interviews, and studies of international best practices
Consequences of shellfish die-offs on seafloor biodiversity
Get PDFCoastal soft sediment habitats contain highly productive benthic communities that provide numerous ecological services. Many of these functions, processes and services are underpinned by the behaviour, density and diversity of the resident macrofaunal community. Climate change has caused heat waves to become more regular and extreme, causing die-off’s of functionally important shellfish beds, potentially generating large shifts in benthic community structure and functioning. Recent studies of the New Zealand intertidal cockle (Austrovenus stutchburyi) dieoff events have focused on cockle population recovery, but there is very little understanding of how the rest of the macrofaunal community responds. To understand how the macrofaunal communities respond to cockle-die offs, a manipulative experiment was undertaken at 23 sites in four estuaries on the northeast coast of the North Island. In late summer, at each site we established a 9m2 control and 9m2 exclusion plot. One year later, we sampled all plots for macrofauna and sediment properties. Results indicate a strong relationship between treatment type and community composition, with none of the exclusion treatments returning to predisturbance community compositions. Furthermore, that recovery was largely estuary specific and community composition following disturbance was highly variable within exclusion treatments. Statistical analysis highlighted that exposure to high intensity wind-wave activity and polychaete dominance within estuaries could explain the relatively improved recovery of Ongare sites within Tauranga harbour. Additionally, there are observable variations in cockle recruitment between sites for both adults and juveniles. This experiment explores whether the removal of cockles, as key habitat forming species, selects for a different macrofaunal community type. The observed changes in community structure can be linked to shifts in ecosystem functioning in these soft sediment habitats
Does invasiveness predict competition outcomes between ecologically similar invasive blowflies?
No full textBiological invasion is a complex puzzle, and its significance is at an all-time high. Current research highlights that the success of invasive species is partly due to their superior performance in key behavioural traits, such as aggression and boldness, especially when compared to ecologically similar native species. However, less attention has been given to differences in these traits among invasive species themselves. Not all invaders are created equal; they vary in their degree of invasiveness, often characterised by the extent of their global spread. If behavioural traits are crucial for invasiveness, it stands to reason that more invasive species - those with greater success - should outperform less invasive ones.
I tested this hypothesis using larval competition between differentially invasive blowfly species. Calliphora stygia has a limited distribution, found only in Australia and New Zealand, whereas Lucilia sericata and Lucilia cuprina (Lucilia spp.) are invaders with almost global distributions. Under direct laboratory competition, the highly invasive Lucilia spp. exhibited fewer body size reductions than C. stygia, regardless of intra- or interspecific competition levels. These findings suggest that competitive traits may exist along a continuum from native to invasive species, increasing predictably with invasiveness. This insight highlights invasiveness as a potentially reliable metric for predicting competition outcomes between ecologically similar sympatric invaders
An Interactive Community Microgrid Model to aid Design Exploration
Get PDFThis dissertation presents a novel approach to microgrid design and exploration through the development of an innovative software application. The primary objective of this research is to empower users to configure and simulate community microgrids, offering multiple time-frame insights into performance metrics, statistical analyses, and pertinent factors aligned with their specific configurations. In collaboration with Ahuora under their third Aim, a key focus is on optimizing factory process heat management while experimenting with renewable energy sources to effectively mitigate overall power consumption. The application developed for this thesis focuses on representing these assets accurately, facilitating the setup/internal optimization of these assets, and allowing the users to tailor the configuration to explore consequences and effects of their changes.
Employing a multidisciplinary methodology, the study seeks to integrate Digital Twin technology tenets, Object-Oriented Programming, Polymorphism, Data Modelling and Visualization, and Complex Power Calculations to formulate a robust and user-friendly software interface. Furthermore, meticulous GUI design and advanced graphing techniques ensure data visualization is both informative and intuitive.
This research culminates in a comprehensive demonstration of the software's capabilities, successfully showcasing its efficacy in meeting outlined objectives. By affording users the ability to dynamically shape and assess microgrid configurations, this study advances the field of sustainable energy management and underscores the potential for optimized factory operations within a renewable energy framework
Microstructure Dual-Refinement and Mechanical Properties Manipulation of TiBw/TA15(Si) Composites by Thermo-mechanical Processing and Heat Treatment
Get PDFTitanium matrix composites with near-α titanium alloy as the matrix exhibit high specific strength and good high-temperature strength. However, the thermo-mechanical processing is limited by the brittleness of the reinforcement, making it difficult to refine the grain size and control the silicide precipitates. The present work aims to prepare titanium matrix composites with refined grain size and silicide particles. To this end, network-architecture TiBw/TA15(Si) composites were prepared using low-energy ball milling and vacuum hot-pressing. After refining the initial lamellar microstructure of the material through a solid solution treatment, the evolution of the TA15(Si) matrix and TiBw reinforcement during the hot deformation were studied. Ideal thermo-mechanical processing parameters in dual-phase region for TiBw/TA15(Si) composites after solid solution treatment was obtained, and the strain distribution in the compressive sample was revealed. Subsequently, TiBw/TA15(Si) composites with fine grains and dispersed silicide particles were obtained using solid solution treatment and isothermal hot-pressing, achieving a simultaneous improvement in room temperature strength and ductility. The influence mechanism of solid solution treatment on the microstructure and properties of the material was analyzed. Finally, TiBw/TA15(Si) composites with different lamellar content and morphologies were obtained through heat treatment of the deformed material. The effect of heat treatment on the microstructure of the material and the influence of different microstructures on the room temperature and high-temperature tensile mechanical behaviors of the material were discussed.
After compositional design through thermodynamic calculation, TiBw/TA15(Si) composites with different Si and Zr contents and a network architecture were prepared by low-energy ball milling and vacuum hot-pressing sintering using spherical TA15 coarse powder and TiB2, ZrB2, and Si fine powders. Silicide particles precipitated on the α/β interfaces in the matrix, and the precipitation amount increased with the increase of Si and Zr element contents. The tensile strength of materials with different compositions ranged from 1012 MPa to 1120 MPa, and the elongation ranged from 1.2% to 6.7%. When the Si content was between 0.3 wt.% and 1.0 wt.% and the Zr content was between 0.3 wt.% and 1.0 wt.%, the materials exhibited good strength and plasticity. By observing the microstructures of different materials subjected to heat treatment at 960°C to 1040°C for 30 min followed by quenching, it was found that silicide particles can be completely dissolved below β transformation temperature when the Si content is below 0.5 wt.%, which is suitable for microstructure control in dual-phase region. Considering the comprehensive mechanical properties and silicide dissolution temperature, a composite with a chemical composition of 3.4 vol.% TiBw/TA15-0.3 wt.%Si was selected for the study of dual-phase region thermo-mechanical processing and microstructure control.
After the solid solution treatment in single-phase region, the initial microstructure of TiBw/TA15(Si) was refined, after that, the high-temperature deformation behavior of the material was studied. The hot compression tests were conducted in dual-phase region at temperatures ranging from 870°C to 950°C and strain rates ranging from 1 s-1 to 0.001 s-1. It was found that the compressive stress-strain curves of the composite in this range exhibited dynamic recrystallization features, and the compressive stress decreased with increasing deformation temperature and decreasing strain rate. Except for the fully lath overheated-microstructure observed at 950°C / 1 s-1, the deformation microstructure of the material under the remaining conditions consisted of equiaxed α grains and residual α/β laths. The microstructure became finer with lower deformation temperature and higher strain rate. Higher recrystallization degree was observed below 910°C at lower strain rates, while the opposite was observed above 910°C. Observation of the microstructure produced by different deformation degrees revealed that the formation of equiaxed grains in the material involved three steps: α/β lath distortion, formation of boundaries within α/β laths, and lath decomposition. The activation energy for hot deformation of the TiBw/TA15(Si) composite after single-phase solid solution pretreatment was determined to be 623 kJ/mol. Based on the constructed processing map, the ideal deformation parameters were determined to be in the temperature range of 900°C to 950°C and strain rates of 0.01 s-1 to 0.001 s-1.
The orientation distribution of TiBw reinforcements during high-temperature plastic deformation in materials has been studied. The rotational behavior of TiBw reinforcements during deformation was analyzed, revealing that the orientation distribution of the reinforcements is influenced by the direction and magnitude of the principal strain applied to the material. The direction of the principal strain determines the principal directions of covariance matrix for the reinforcement's orientation distribution, while the magnitude of the principal strain determines the parameters in the probability density function. Based on these findings, a method was proposed to calculate the local plastic deformation in materials using the orientation distribution of TiBw reinforcements. Error analysis through computer simulations showed that this method exhibited good accuracy in the range of 20% to 80% compression strain. Using this method, the strain distribution in hot-deformed TiBw/TA15(Si) composites was analyzed, and the accuracy of the calculations was confirmed by comparing them with the deformation of the network structure of TiBw.
Based on the results of hot compression tests, TiBw/TA15(Si) composites were subjected to a solid solution treatment followed by isothermal hot pressing at 920 °C and a strain rate of 0.003 s-1 with 75% height reduction. This process yielded a microstructure with fine equiaxed α grains and dispersed fine silicide particles, with an average grain size of 1.6 μm and particle size of 70 μm, respectively, achieving a dual-refinement of both α grains and silicide particles. The composite exhibited a yield strength of 1100 MPa and an elongation of 7.7%. A comparison showed that the solid solution pretreatment led to finer grains and more dispersed silicide particles in the material after isothermal hot pressing, resulting in a significant increase in yield strength.
Heat treatment of the hot-pressed composite in the range of 980 °C to 1050 °C revealed that higher temperatures led to higher contents of α/β laths and coarser microstructures, while faster cooling rates resulted in finer lath structures. Water quenching after the heat treatment at 1010 °C for 30 min produced excellent room temperature strength and ductility, with a tensile strength of 1350 MPa and an elongation of 6.7%. Slip trace analysis and transmission electron microscopy analysis revealed that the equiaxed microstructure in the material facilitated multi-system slip, enhancing deformation uniformity. The prismatic slip in lamellar microstructure obtained with air cooling was suppressed by the Burgers orientation relationship, the strain-softening of the lamellae resulted in deformation dominated by single-system slip and strain localization. The transformed β phase obtained through water quenching exhibited limited deformability, which was primarily accommodated by the prismatic slip of primary α laths. High-temperature tensile tests under different conditions showed that decreasing the deformation temperature, increasing the strain rate, refining the grain size, and decreasing the α/β lath content transform the deformation mechanism into grain boundary sliding, which significantly enhances the deformability of TiBw/TA15(Si) composites. The composite with fine equiaxed microstructure could achieve an elongation up to 348% at 800 °C and a strain rate of 0.0003 s-1, which showed a good potential for superplastic forming at low temperatures
The Te Puninga Fault, Hauraki Plains: a new seismic source in the low seismicity northern region of New Zealand
Get PDFIn this study, we provide the first field-based assessment of the seismic potential of the Te Puninga Fault, Hauraki Plains, Waikato region. Initially considered to be part of the nearby Kerepehi Fault, our new mapping and field data suggest the Te Puninga Fault is independent. A new net slip rate value of 0.25 mm/yr, based on geomorphic data and evaluations from two paleoseismic trenches, is slightly higher than previously considered. Comparisons of geomorphic expression between the two faults suggest that the slip rate currently assigned to the Kerepehi Fault could be underestimated. The earthquake magnitude estimated here for the Te Puninga Fault (Mw 6.9 ± 0.35) is based on a characteristic earthquake model. New PGA and MMI estimates here are only slightly larger than those published prior to this study. Although ruptures of the Te Puninga Fault are infrequent (derived recurrence range of 3000–11,500 years), and thus its hazard is low, with this paper we wish to enhance the community awareness to prepare for the rare large earthquake in the region. We also recommend that this new information is added to fault databases used for seismic assessment
Landfill leachate treatment: Using sequencing batch reactor technology to remove high ammonium concentration
Get PDFLandfilling requires various consents and regulations in order to operate most effectively and cause minimal environmental issues to its immediate surroundings. The contaminated liquid produced from precipitation seeping through the layers of waste in landfills are generally called landfill leachate or leachate. Sequencing batch reactors (SBR) are fill-and-draw activated sludge systems that facilitate wastewater treatment in a singular reactor, while utilizing a sequence of different phases to create aerobic, anoxic, and sometimes anaerobic conditions. Multiple studies have been done that demonstrate the capacity of SBRs to treat wastewater for varying strengths of wastewater and concentration of contaminants, including ammonium. The objectives of the research are to: 1. run a lab-scale sequencing batch reactor to treat ammonium concentrations similar to that of landfill leachate; 2. design a full-scale sequencing batch reactor for landfills based on the bench-scale reactor’s ammonium removal potential; and 3. analyse the viability and economic feasibility of a SBR for treating landfill leachate.
Two lab-scale SBRs are used in the experiment. SBR 1 was run for 250 days of operation, while SBR 2 was run for only 130 days. These achieved ammonium removal at influent ammonium loading as high as 720 mg/L, and the SBR achieved ammonium removal efficiency of 90% to 100% with a TSS of 17 to 18 g/L during this most stable period of operation. pH control was required at higher influent ammonium loadings above 300 mg/L. Removal rates over the stable periods of operation are calculated to be at 1.65 and 1.55 mg NH4+ removed/g TSS/ per cycle for SBR 1 and 2, respectively. An ammonium removal rate of 0.0508 mg NH4+/L/min is calculated based on measurements using an ammonium ISE probe. Inhibition in ammonium removal due to low pH is observed. With extended aeration and pH control the ammonium removal continued as long as pH is maintained above 6.5. The oxygen consumption rate is also found to be at 0.01 mg DO/L/min, while the average mass transfer coefficient of O2 at 0.0144 min-1, and the percentage of oxygen transferred from gas to the mixed liquor calculated to be at 14.8%.
The full-scale SBR design is based on rates calculated from the experimental set-up and approximate leachate flow rate, based on precipitation, in the Waikato region. An area of 49 hectares landfilled is considered, which is similar to one of the class 1 municipal sanitary landfills in the region. A landfill leachate ammonium concentration range of 600 to 1500 mg/L is considered for the full-scale SBR design. The full-scale SBR is calculated to require a working volume of 8168 m3. The capital and operating cost of which shows high economic feasibility, and is estimated to be cost-effective compared to the cost of offsite treatment
A culturally responsive research move to enable Pacific voices to be heard: a research note
Get PDFResearchers in the field of education have increasingly come to value the views and experiences of students, and hearing from the students themselves. This research note explores the challenges a researcher sought to gather student voice from Cook Islands tertiary students. The combination of research design and cultural mores meant Cook Islands participants faced barriers and could not comfortably talk about improvements they would like to see in tertiary assessment practice. On exploration, an adjustment to the research design was made that was culturally accepted and enabled participants to speak their minds openly. The findings are discussed, and recommendations are proposed that may assist future researchers working within cultural worlds in ways that allow the participants to speak openly, enabling their voices to be heard
Canine scent detection: Lung cancer target acquisition
Get PDFA growing body of research has developed over the last 30 years exploring disease scent detection using animals. Research project methodologies and results in this field vary significantly, including some which are quite promising. Critiques of aspects of current and past practice in disease scent detection using animals inform recommendations for the development of scientifically robust standard operating procedures in this field. Greater standardisation and transparency of practice has the potential to strengthen and clarify disease scent detection results. My primary aim was to contribute to this standardisation by using a theoretical understanding of concept formation and learning acquisition to inform three experiments in which pet dogs (Canis lupus familiaris) were trained to detect the presence of lung cancer in human breath and saliva samples. Operant conditioning processes and an automated apparatus were used to train and test the dogs. Data for all three experiments were collected concurrently. The experiments involved: designing a process for evaluating sample comparisons; evaluating the efficacy of sample re-use for training purposes; and developing a mathematical model to support decision-making about the transition from training to testing of detector organisms. Firstly, we evaluated the comparative utility of human breath and saliva samples to train and test dogs for lung cancer detection. Signal detection measures were used to gauge the dogs’ target acquisition and concept formation during the training process. The dogs acquired the lung cancer target concept more quickly from breath samples, but also demonstrated higher-than-chance recognition using saliva samples. Secondly, we systematically evaluated the effect of breath sample re-use on dogs’ performance during lung cancer scent detection training. There were no significant changes associated with the detectability of the target across samples re-used up to four times, and observed changes in performance were small. Finally, we explored methods of evaluating when a detection animal is performing at or near the highest accuracy of which they are capable with a view to identifying the optimal point at which to transition from training to testing. A quantitative model was most informative during our work training dogs to detect lung cancer. Ongoing testing of the dogs’ abilities using novel samples occurred during training. However, the final testing (and intermittent training) needed to measure and maintain the dogs’ performance against asymptotic predictions was beyond of the scope of the current project. Notwithstanding this, each of the experiments described herein provides both specific data on the performance of our dogs, and procedural information about ways in which different components of scent detection methodology using detector organisms could be strengthened. Both of these resources could be used in concert with other methods of scent detection. Relevant theory on concept formation was reviewed and used to plan and interpret the acquisition of the target scent. Likewise, theoretical explanations of target acquisition and associative learning informed our analysis of data. In this way, each of these experiments contribute to improving practice in the field of disease detection by providing model procedures from which other methods for evaluating sample types and the reuse of samples could evolve. The development of a standardised measure for determining when to stop training and start testing a detecting organism might also be applied to a wide range of learners in myriad contexts to good effect
Marine stressor and receptor interactions: A new approach to incorporate multiple stressor impacts into marine spatial management
Get PDFSoft sediment benthic ecosystems are highly productive habitats which provide humans with a variety of valued resources and ecosystem services globally. However, coastal environments are subject to ongoing and increasing levels of anthropogenic stress which urgently needs to be quantified and strategically managed to balance socioeconomic resource interests. To support a more holistic approach to Marine Spatial Planning and better inform management decisions, spatial assessment approaches are needed which quantify the accumulating impact of multiple stressors on coastal species and habitats. This thesis investigates stressor-induced change in the density and distribution of subtidal benthic invertebrates from two globally pervasive stressors (sedimentation and bottom fishing), to develop spatial assessment tools useful to inform marine spatial management decisions.
For many benthic species, their functional capacity is inherently density-dependent, and environmental stressors can impact population density, hence limiting the functional capacity of species and their ability to contribute to ecosystem processes and overall ecosystem health. A holistic approach to MSP needs to address the ways in which humans can cumulatively use, and also impact the environment, but it is difficult to measure the impact an environmental stressor can cause without first quantifying the current density and distribution of key species that they effect. Furthermore, it can often be challenging to obtain species records measuring abundance, density, or species richness within certain geographical locations, due to data scarcity, even if more data is available over a broader spatial scale. Probability of occurrence, abundance, and density was predicted using Species Distribution Models (SDMs) for seven functionally distinct benthic invertebrates, over two different spatial scales to compare the difference in model performance and usefulness of predictions made using data-rich national scale models compared to data limited regional scale models. Results indicated that neither occurrence nor abundance SDMs performed consistently better at either scale across all taxa models, demonstrating the challenge of working in-data limited environments. Models which achieved the more optimal predictive performance across spatial scales were selected to be combined into a regionally useful density model (i.e., regional data-derived occurrence model * national data-derived abundance model) highlighting the utility of a multi-scalar approach.
Knowledge of how multiple stressors impact marine species and modify habitats over time is critical, to support management and mitigation of anthropogenic stressors. Bottom fishing and sedimentation stress are two globally pervasive coastal stressors. The transportation of terrestrially sourced silt, mud, and clay into the coastal environment from inadequate land management can alter sediment biogeochemistry, and alter macrofaunal community composition, which can lead to the smothering of seafloor communities. Bottom fishing can directly damage and disturb seabed habitats, reducing the abundance of macrofaunal communities, and can lead to homogenisation of the seascape. A spatially explicit model including correlative stressor-response relationships were applied to simulate single and multi-stressor impact scenarios over a temporal period of four-years to predict the change in density, distribution, and recovery for different stressor combinations and magnitudes. Models focussed on three functionally distinct coastal seafloor invertebrates that varied in stressor response and recovery time. All taxa exhibited different stressor responses in terms of density change, and the spatial distribution pattern of density values was affected, informed through empirically derived stressor-receptor response curves. The greatest modification to taxa density occurred across the shallow coastal environment, near shore, for habitats that were predicted to have high density to begin with. Fishing was the more dominant stressor and overlapping fishing impact year on year resulted in little to no recovery. For sensitive emergent epifauna (Callyspongia), sedimentation stress was almost as impactful as fishing, highlighting that greater management consideration should be given to the compound effect of slow-acting, accumulating stressors, even in scenarios where a single stressor is more dominant.
Failure to adequately identify and mitigate the effects of multiple stressors increases the risk of focussing conservation efforts on areas that could become ecologically diminished in the future. To ensure that global biodiversity conservation targets are upheld under ongoing anthropogenic conditions, practitioners must identify robust and ecologically resilient habitats that will persist over time as part of a systematic prioritization approach. A comparative spatial prioritization assessment was performed to test the utility of using density SDMs that had been modified by stressor impacts (stressor-impacted predictions) to drive a spatial prioritization using Zonation, as opposed to using unimpacted density SDMs (the conventional method). Utilising stressor-impacted predictions within the prioritisation assessment increased conservation efficiency, and thus spatial accuracy, to help prioritise high-density areas that showed resilience to stressor impacts over time (from 4 years of successive stress). This analysis highlighted that conventional prioritization approaches may no longer be sufficient and may prioritise habitats that experience density loss under stressed conditions, undermining conservation effectiveness. Incorporating multiple stressor effects that have accrued over time can help identify areas that are likely to retain a higher total density into the future, to support long-term conservation objectives. Incorporation of spatially explicit stressor effects using taxa stressor impacted density predictions helps identify ecologically rich and resilient habitat areas that persist within the broad footprints of stressors, instead of avoidance, which is often promoted by conventional approaches to minimise conservation cost.
Collectively, this thesis demonstrated the utility of novel modelling approaches which integrate the combined and accumulating effects of anthropogenic stressors on coastal species and habitats to help inform MSP decision-making. It also highlighted the range of possible implications to benthic species and coastal ecosystems if anthropogenic stressors are not adequately identified and managed